Steam or gas turbine



1937. A. WETTSTE IN STEAM OR GAS TURBINE Filed Jan. 17, 1 936 6 Sheet s-Sheet l Oct. 19, 1937. F. A'. WETTSTEIN STEAM OR GAS TURBINE Filed Jan. 17, 19567 6 Sheets-Sheet 2 &E /W/ .m mm

Oct. 1937. F. A. WETTSTEIN STEAM OR GAS TURBINE Filed Jan. 17, 1936 6 Sheets-Sheet 3 Oct. 19, 1937. F. WETTSTIN &

STEAM OR GAS TURB INE Filed Jan. 17, 1936 e Sheets-Sheet F. A. WETTSTEIN STEAM OR GAS TURBINE Oct. 19, 1937.

Filed Jan. l7, 1956 6 Sheets-Sheet 5 MIN' Oct. 19, 1937. F w s 2,096,079

STEAM OR GAS TURBINE Filed Jan. 17, 1936 e Sheets-Sheet s I allahun- Patented Oct. 19, 1937 UNITED STATES PATENT OFFICE STEAM OR 'GAS TURBINE Application January 17, 1936, Serial No. 59,635

In Germany January 17, 1935 n 19 Claims. (01. 253-7 3) i The present invention relates to rotors for radial flow steam or gas turbines, and more particularly to rotors of the type Wh'erein the blades extend in the form of centrifugal catenary lines between axially spaced blade carrying or retaining rings and the rings are interconnected by struts.

In order to attain the highest possible peripheral velocities, it is desirable that the rotor construction be such that substantially only tensile stresses arise in the blades and only compression stresses in the struts. For the same reason, it is desirable that the hearing or reaction forces of the blades and struts exert no bending moments on the blade carrying rings, so that substantially only purely tensile stresses arise in these rings also. The principal object of the invention is therefore to provide a novel rotor Construction capable of fullling these conditions which, in hitherto known constructions of radial flow, curved blade rotors, it has often been difiicult or impossible to meet, particularly when the blades extend in relatively fiat curves. r

In order that'the nature of the invention may be more clearly understood, the following explanation of the conditions 'existing in a rapidly rotating turbine rotor should first be considered;

Since the two blade carrying rings are interconnected only by the blades and the struts, the axial Components of the bearing forces of the blades and struts arising through the action of centrifugal force must nullify or balance each* other. The resultants of these bearing 'forces exerted on the carrying rings are thus directed radially and are each of a magnitude equal to half the centrifugal load of blades and struts; The positions of the effective points of application' of these resultant forces are determined by the points of intersection of the hearing forces of the blades and struts; The load'on the ring must be nullified or balanced by an 'equally great and oppositely directed tensional force, which is produced by a corresponding load or strain on the blade carrying rings. This tensional :force is the resultant of all tensions over the ring cross secmeans atperipherally spaced points.

and i the greater the distance becomes between these intersecting points and the centers 'of gravity of the crosssections of the ring, whereby the I rotary moments become correspondingly greater. These rotary moments tend, so to speak, to overturn or tilt the blade carrying rings out of their normal'planes perpendicular to the rotor axis. Additional bending tensions can thereby arise in the carrying rings as Well as in the blades and struts. 3

'These defects aresovercome .according to 'th'e present invention by locatng the attachments of the struts to the carrying rings wholly or partially between adjacent blade attachments, and/or by providing the blade carrying rings on their inner adjacent sides with additional loads for example, by subdividing the grid-like strut assemblage peripherally or circumferentially, or by cutting grooves into portions of the carrying rings in such manner thatthe resultants of the hearing *forces of all elements, such as blades; struts, etc.,.carried by the blade carrying rings pass through or approximately through the teni sional centers of gravity,*or oenters of centrifugal loads, of the cross sections of the rings. The overturning or tilting moments for th blade carrying rings thereby disappear, and only' I stresses, in contrast to bending stresses, the,

strength of the material is completely utilized,

thereby enabling the use of the lightest possible Construction; This is an advantage of great imi portance in the Construction of turbine rotors and permits of attaining high peripheral Velocities. In addition, the use ,of smaller cross sectionsof material permits the making of allowances for 'retainingthe heat tensional forces with-' in low values; r

As previously indicated, the occurrence of bend-' ingtensions isavoided in the present invention, for example; by subdividing the'strut anchoring' The attachingarrangement of thestruts to the blade carrying rings then forms an additional load on the inner adjacent' sides of the rings, which load acts' oppositely to the overturning momentex erted by the blades and struts on the'rings. i

By subdividing the strut connections peripherally into a number of equal parts, manufacture of the rotor is also made less expensive, since' cheaper operative methodsmay be employed, and

-a "saving in material is effected,

e These and otherradvantages and features of I the inventionwill appear more upon consideration of the description of the various embodiments illustrated in the drawings which follows. Referring now tothe drawings, Wherein like reference characters indicate like parts throughout o the several VieWs:-

Fig. 1 isa cross section of a portion of one form i of rotor of a radial flow turbine constructed in accordance with the invention, the section being taken substantially on a plane passing through the rotor axis; x

i Fig. 2 is a plan view of a portion of the subdivided strut assemblage of the rotor of Fig. 1; Figs. 3' and 4 are views similarto Figs. 1 and 2 of another form of rotor embodying the invntion,

Fig. 3 being taken substantially on line III-III of Fig 4';

F'igs. 5-8 show still another embodimnt of the' invention, Figs. 5 and 7 being sections taken substantialiy cn lines V-V and VII-VII; respecr tively, ofgFig. 6, thelatter being a plansview of a portion of a strutassemblage similar to that shown in' Fig. 1 with the inner portions of the 'blade carrying rings shown in section, and Fig. 8 being a plan View of one element of the strut assemblage of the rotor of Figs, 5-7;

Figs. 9 and 10 are sectional and plan Views, respectively, of a portion of another form of strut 'assemblage: e

Fig. 11 is an elevation of a still different strut element, whilerFig. lz illustrates the manner of attachment thereof to the blade carrying rings;

Figs; *13-15 illustrateanother formof strut assemblage; Figs. 13, and l'' being sections taken substantially on lines XIII- XIII and XV--XV, respectively, of Fig. 14 which is a plan View of the struts With the blade carrying rings shown in-section; o

Fig. 16 'is a planview of a portion of still another strut assemblage;

Figs. 17-20 are views similar to Figs. of another form of rotor embodying the invention;

r i Fig. 21 is a plan View ofa split bar or rod fromwhich the strut ;of F'ig..20 maybe economically formed; g e

Figs. 22'and 23 are sectional and plan views,

respectively,-of'a portion of a still difierent rotor i Fig. 26; r

Construction, the rotor blades in Fig.; 23 ,being broken away to showthe strut Construction. Fig.

24is ajplan View of one of ?the strut elements of Figs. 22 and 23; r, i i

Figs; 25-27 show a portion of another rotor constructed in accordance with `,the invention; Fig. 26 being a plan View and Figs. 25. and 27 being sections taken substantially on lines XXV- XXV and l XXVII-XXVII, respectively, of

Figs. 28-30are Views similar to Figs. 25-27-01 ,anotherrotor em'bcdying the invention; and,

Figs. 31-35 are ;sectionaland plan Views showing'details of Various'other forms of strutelements of tubular Construction adapted for use in ;connection with the invention.

Referring first to Fig; 1, i designates a curved turbine blade which is attached or anchored at ,both ends ,by means ofintermediate members 2 'and 3 insuitable circumferentially extending retaining V grooves formed in the axially spaced blade carrying rings 4 and 5. The blades are preferably made .of relatively thin 'sheet metal and during rotation are subject to the influence of centrifugal force which in turn sets up tensile forcestencling to pull or draw together the two rings 4 'and 5.' This isiprevented, however, bythestrut assemblageconsisting of the X-shaped 'members &and 1 which are subject to compressic The? obliquity, or X-0rm,of the struts serves to' increase the rigidity of the rotor assemblage of blades and rings. As shown, the struts also bend or sag toward the interior of the rotor whereby, no bending stresses, but only purely pressure stresses, arise in the struts under the' influence of their centrifugal load and their lateral shifting toward each other. I

As clearly shown in Figs. 1 and 2, the ends of each pair of struts 6 and 'i are connected with a pair of arcuate attaching members or feet 8 and 9 having outwardly turned lips or fianges which fit in corresponding grooves formed in rings 4 and 5 and are secured therein by rammed-in packing 'material lflland'll.

Fig ltalso showsby means of Vectors the bearing forces which are set up'when the rotor is in operation. e For example:l2 designates the tensional`force exerted through the action of centrifugal force by blades "I *on carrying ring 4,

While l3 represents the radial force exerted by the intermediate members`2. l4iis the resultant of forces l2 and !3. On the other hand, the struts 6 and 1 'exert aradial force on thering 4, .while the anchoring feet 8 and 9 produce radial loads 16. The resultant ll of the forces |5 and IS is the total reaction force exerted by the strut' The point of intere section !8 of this reaction force I'l and the e'xassemblage on the' 'ring 4.

tension of resultant force ;l4 determinesthe efiective point-?of application .of the total resultant !9, which, for convenience, is shown at the right on' ring 5. This resultantload s is maintained in equilibrium .or balanced bythe' equally great and oppositely directed tensional forcen of the ring.

In the ioregong case, -as seen, the point of application !8 of the resultant is of the hearing forces lies in the same plane perpendicular to the` i rotational axis of the rotor With the centero f gravity 2`| of the ring cross section; consequently, there, is no rotary or overturning moment exertedv on the carrying ring\ If, in .contrast thereto, the

strut assjemblage is' made in one piece, asin known arrangements, with the feet 8 and!) united with" acomplete ring; the rings become self-hearing and the points of intcrsection of the bearing forces obviously shift to positions such as that occupied. by a point 22 in Fig. 1. i Since this point does not lie in the same ra'dia1 plane with the center of gravity of the ring, there 'arises in the ring ?a rotary moment which-tends to overturn or tiltit.: i

, 'It is thus apparent, as'shown on Figs. 1 'and 2, that by subdividing the* strut assembla'ge ,at peripherally spaced'pcints';additional leads arise at i the inner adjacent sidesof rings 4 and 5 through the 'strut feet 8 anclV9,.`Which additional loads' ,oppose or entirely eliminate therotary moments'- exerted on the rings by the blades andgstruts. e

Subdvision of the s'trut assenblageinto a number of partia] elements, as shown in'Fig.,2,- a1so If the latter is made in one piece, the' struts'must' be machined from a solid rim with proportionately Partial` larger labor costs and waste of material. elements like that shown .in Fig. 2,;however, may

be made by much less 'expensive proceduresjfcr reduces the cost of production of 'this assemblage 5 example, by die or drop forging, and the'presult i is also aconsiderable economy of material. In

additiom'themanuacture of alarge number of' i small parts is per se an eccnomical measure-as Compared with the production 'of a large "complicated'structure.` i p V v 5 In the-ex'emplary. embodiment shown' on. Figs.

3 and 4, on the other hand, thestruts 23 are made" integral with the blade carrying rings 24 and 25."

The latter are partially cut through at their inner adjacent sides by peripherally spaced, radially extending groovesor notches'z and 21, the resulting projectio'ns or shoulders 28 and 29 formin'g Weights on the inner sides of rings 24'and 25. These weights are equallyias largevand; have the same action as the strutfeet 8 and 9 of Figs. 1

and. 2, in that they nullify the rotary moments:

exerted on the rngs bythe blades and, struts. The grooves thus formed in the 'carrying rings may be suitably provided at their inner ends with enlarged grooves or spaces asindicatedat 30 by drilling or boring, thus reducing the danger. of fracture of the rings.

In the embodiment of Figs. semblage is also subdivided peripherally into X- shaped members 3l. The feet 32 of 'these mem- -bers are so formed that they fit ,into circular tracks or grooves turned in theinner adjacent sides of the rings, and are retained therein by' The feet of the rammed-in packing pieces 33. X-shaped members may be made so that they r ,abut each other peripherally, 'as shown for the adjacent members 3| and 34 in Figs. and 6, or there may be left between the feet of two adjacent members an intermediate space, like that between the members 34 and 35, said space being ;filled with the filler material or spacer member 36 so as to maintain the proper positions of the members. In order tofacilitate production and avoid heat tensions on hardening, it may be preferable to make the feet 31 and 38 of the X-shapecl 1 member 35 separately, as shown in Figs. 6 and 8.

With this construction, filler members 39 (Fi 6) i are inserted between the adjacent strut feet 31 and 38. V Figs. 9 and show a member of a strut assemblage having a -form approximately that of the capital letter N; and it is obvious that the form of the strut assemblage maybe widely varied, ,as may also the manner in which the 'assemblage is subdivided. i V v In the embodiment of Figs. 11 and 12, the struts 40 are each made separately 'and provided with dovetailed feet 4l which are inserted radially from v the ,inside outwardly .in corresponding grooves;

formed in the bladecarrying rings.

In the embodiment of Figs. 13- 15, the X-shaped members of the strut assemblage are obtained'by welding bent struts 43 and 44 together at 42. The

dovetailed feet 45 thereof are inserted radially, inside outwardly in ;corresponding grooves formed in the retaining rings. The strut` from the feet and the grooves are preferably, as shown on Fig. 15, constricted or tapered-from the inside outwardly so that the struts 'are clamped tightly in the rings. In casethe load through the strut attachment is undesirably great; a portion of the ring material may be machined off, as indicated at 46. I

Fig. 16 shows two members 50. i v i In the Construction shown inFigs. 17, 18 and 19, the X-shaped members 5l of the strut assemblage are inserted by their dovetailed feet 52 in rad'ally directed grooves 531formed in the blade carrying frings. The grooves 53 do not pass entirely through the rings in a ra'lial direction but' are'open at their rad'ally innermost ends and closed at their radially outermost ends', thus determining the radial position of the X-shaped of atstrut assem-, blage wherein each is made by welding together four suitably 'shaped and bent rods 41, 48, 49 and the grooves witha frictional fit and upon rotation parts. ofthe strut assemblage. :With .this. con-, struction, the dovetailed feet may be forced ,into

of the turbine rotor will be urged thereinto even* more' tightly by centrifugal force.

It is obvious that there'is no need in this instancefor 'any specific fastening means to hold "the feet inthe grooves, although, of course, packng members of any'well known Construction may-be used .if desired. 'The struts 5! :in this embodiment arer also' beveled off on two opposite sides, as shown. This is advantageous in those cases where thetturbine driving medium traverses the struts, not r-adially, but at 'accertain angle relative to the peripheral direction of the strut assemblage.

Fig. 20 shows one of the X-shaped membersl of the strut assemblage of `Figs. 17-19. As shown in.Fig. 21, this member, in order to savematerial, mas be made, for example, of arod which is split atboth ends as indicated at' 54and 55 but* hot' in thegmiddle, the divided ends then being spread -apart' and upset attheir extr'emities to form the. feet 52.

Figs. 22 and 23 show a portion of a rotor wherein the strut assemblage is again subdivided into partial members 56, one of which is shown'in detail in .Fig. 24. Since this Construction is adapted for a relatively large rotor, the members of 'the strut assemblage are parti-allysupported by a reinforcing ring` 51 disposed intermediatethe blade carrying rings 60 and 6 I.. This ring is itself retained in its proper position by the guide lugs 58 projecting outwardly from the members 56; v

The blades 59, after the rings 60 and 6! are assembled with the strut assemblage, are inserted by their dovetailed feet in correspondingly formed grooves 62, and thereupon Secured and` retained in said grooves by key members 63 (Fig. 23) which are inserted into the grooves .from both ends. In this embodiment also, the feet 64 of ,the struts together with the intermediate members 65 (Fig.

22) form,in accordance with the invention, loads on the inner adjacent sides of; the rings '60 and'- S'Lths' preventing the occurrence of moments planes at right angles to the rotatlonal aXis of the e turbine with the Centers of centrifugal loads (centers'of gyration) of the rings. In this case) the struts; 68 and 69 are made integralwith the rings 66'and 61 as well as with the intermediate retainingring 'IL The blades TU are inserted by their dovetailed feet in corresponding obliquely dire'cted grooves 12 in rings 66 and 61. Parts of grocVes 72 thereby extend between theattaching points' of the struts, as clearly shown in the drawings. .This Construction is well adapted for Very high peripheral velocites, thus particularly.

for the last ring of blades of a turbinejas the I 'extra load on the blade carrying rlrgs created by V separate feetcis absent. ,The telescopic, or over-` V lapping attachment of 'blades and struts of further advantage in that the radial extent ofthe rotor is reduced, which'is of greaterimpor tance withradial flow turbines and renders pos .sible jan increase of the sum ofthequarestof:

the peripheral velocities. i

V Figs. 28-30 show a Construction wherein over turning moments on the rings 13 and 'Mare precluded by partially crossingor overlapping the curved blades 15 andthestruts 16 at their ends.

'In this exemplary embodiment, the struts 'mare not integral with the retaining rings 13 and 14, but are Secured thereto by means of enlarged feet 11 which are inserted in peripherally extending grooves or tracks 18 and retained therein bypacking as indicated at 19.. Feet 11 have the same form as the intermediate spacing members 80 and serve simultanously therewith ?for spacing and retaining the enlarged ends of blades'l in grooves 18. Finally Figs.` 3-35 indicate ;various forms` oi strut? construction .using tubular members for the struts; .As previously; stated, the struts are subjected to compression `stresses and therefore exposed to the danger offracture. For this rea.- son the use of tubing is particularlyadvantageous; in addition, struts made of tubing are light 'in weight as ,Compared with their strength.

'As Fig.'31 shows, the strut tubes 8! may be inserted in hoies drilled or otherwise formed in the feet 82 and welded to ether therewith. On

V the other hand, the feet may have the form shown area of said ring. e i I i 2. A rotor constructjion according to claim 17 wherein the ends of said struts are connected-to i in Fig. 32, made by forging', and the 'tubes 83 may be forced or 'pressed on` the tubular' extension members 84 of the 'feet 85,' or may be screwed thereon. i i i Fig. 33 shows an X-shaped member of 'a strut assemblage whichis made of tubes in the above manner, the tubes 81 being united at the center of the strut by an X-shaped member 86. As shown in Fig. 34, the tubular struts 81 are preferablyof elliptical cross section, the greatest axisofthe ellipse being directed substantially radially;

whereby the resistance oiTered to the flow of the turbine driving medium is reduced to a minimum.

Fig. 35:shows two simple strut tubes which ar made in similar' manner.

- Although a? number 'of different rotor-'and's'trut constructionsvhave been described and illustrated in detail in the accompanying [drawings, it is to' be texpressly understood that these .drawings are for purposes of illustratiorr only? and are not to" be construed as defining the scope of the inven- `tion which is obviously capable of a variety of mechanical embodiments. Reference is therefore to be had to the appended 'claims for a definition of ,the limits of'the invention. What is claimed is: i

- i 1. In arrotor for radial flow turbines, the com'-` bination of a pair of axia'lly spaced rot'atable blade carrying rings; a plurality of blades anchored at their ends to and extending in catenary-likeform between said rings, and a plurality of struts interconnecting said rings, said blades and struts being so constructed and arranged reiatively to `one another and so attached to said rings that the resultant of the forces acting 'on'each ring during i rotation thereof is directed substantially through I f loads of thesectional the center of centrifugal said' blade carrying ,rings cat points intermediate the points'of anchorage of saidbiade ends to said' rings. e g e 3. A rotor Construction according toclaim 1 wherein the ends of said struts lie between and are connected to said blade carrying rings at points between the blade ends so as to overlap aoeew'zo; ,i i

therewith when viewed a circumiere'ntial direc-j' tion. i r

4. A rotor construction according to c'la'imi wherein the struts are formed in separate arcuate sections peripherally of -the rotor and each section is Secured to 'said' blade' carrying :rings a independently of the other sections.

5. A rotor 'Construction according'to ate sectionsperipherally of'the rotoryeach of said strut sectionsbeing substantially` X shaped in i claim 1 wherein the' struts' are formed in separate `arcu-` plan and having'enlar'ged feet `formed-at the ends of'the crossed elements thereof fo'r attachment to saidblade carrying rings.

6. A rotor Construction according to claim 1 wherein said struts are tubular in form and have Secured to their ends enlarged feet by which they are connected tosaid blade carryingrings.

7. A rotor Construction according to :claim 1 e wherein saidblade carrying rings are provided peripheris' thereof in which theblade ends are 20 with blade 'retaining grooves 'formed inthe anchored, at least a portion of each ofgsaid p grooves passing between the 'points of attachment to said 'ring of two adjacent struts.

8. A rotor construction= according to claim' l carryingrings are specially loaded in such-manher-as to adjust the positions fthe result ants of i the forces actingon each ring during rotation' from those that would exist in the absence of said speciai loads to those in' which the resultants pass substahtially through the Centers of centrifugal leads of the sectional areas of said rings.

9. A rotoreconstructionaccording to claim 'I p wherein the inner adjacent sides' of said blade I whereinthe inner adjacent sides of said" blade i carrying rings are provided with retaining grooves in which the ends of said struts are anchored;

10. A rotorconstructi'onaccording toclaim i i wherein the inner adjacentsides of said'blade carrying rings are providedgwith a plurality of circumferentially' spaced, radially extending retaining grooves` in which theends `of' said struts are anchoredg i 11. A rotor Construction' according to claim 1 wherein the inner' adjacent` siides of said blade i 'to those in which the resultants pas 'substaritially through the centerjs of' centrifugal loads 'of the sectional areas of said'rings;

13. A rotor ,construction accord ng toclain'i 'l wherein each of saidblade'carrying rings is proi vided witha circi mferentiallyextending retaining groovefo'rmed in? the periphery thereof in which the ends of both said blades and said struts are anchored. i V f14. A rotor Construction according to claim 1 wherein for 'radiaLfiow turbines comprising each of said blade carryingrings'is provided with* a circumferentially extending retaining groove' V formed in' the periphery thereof; iniwhich the ends of both said bladesand said struts are anchored, saidstrut ends being so constricted as to also constitute means'for spacing the blade ends the required distances apart and retaining the latter in said grooves.

15. A rotor Construction according to claim 1 wherein each of said blade carrying rings is provided with a circumferentially extending retaining groove formed in the periphery thereof in which the ends of both said blades and said struts are anchored, said strut ends being'enlarged in the circumferential direction of said rings and being inserted in said grooves between adjacent blade ends whereby said strut ends also constitute means for spacing the blade ends the required distances apart and anchoring the latter in said grooves. y i

16. A rotor for radial flow turbines comprising a pair of axially spaced rotatable blade carrying rings, a plurality of blades extending in catenarylike form between said ring's, and a plurality of struts interconnecting said'rings, said struts be ing divided into a plurality of separately formed sections peripherally of the rotor with each section removably secured to said rings independently of the' others.

17. A rotor Construction according to claini 16 wherein the blade carrying rings are provided with a plurality of retaininggrooves in which the ends of said strut sections are anchored, said i grooves and strut ends being so constructed and arranged that the latter may be inserted in the former by a radially outward movement of each i 19. A rotor Construction according to claim 16' wherein each of said blade carrying rings is pro-' vided with a retaining groove in which the ends of both the biades and the struts are Secured.

FRITZ ALEXANDER WET' 'STEIN. 

